Google| Subject | Re: ISO value names are becoming ridiculous |
| From | Whisky-dave |
| Date | 01/11/2016 14:45 (01/11/2016 05:45) |
| Message-ID | <a7ec4c27-2cf0-40ff-b6df-dd1624d9674a@googlegroups.com> |
| Client | |
| Newsgroups | rec.photo.digital |
| Follows | Savageduck |
On Saturday, 9 January 2016 14:50:46 UTC, Savageduck wrote:
SavageduckYes me too, it sort of made sense and everyone else seemed to agree in those days.
On Jan 9, 2016, Sandman wrote (in article<sandman-6fa741d6993cb0551719b4a6ebf436b1@individual.net>): <Yeah I snipped a bunch of stuff. What I had to say is related to the cite below.>SandmanSavageduck
<http://camerapedia.wikia.com/wiki/Film_speed> "With an arithmetic scale, the exposure decreases in direct proportion to an increased speed - so a doubling in film speed requires half the exposure. For example if an exposure of 1/250s at f.8 is required for a 100 ISO film, a 200 ISO film would require either 1/500s at f.8, (or 1/250s at f.11) and 400 ISO film would need 1/1000s at f.8 for the same scene.
A logarithmic scale increases a fixed amount for a doubling of speed - 24 DIN is twice as fast as 21 DIN, and 27 DIN is four times as fast as 21."
All the other parts of this discussion aside, the cite above is how I have always understood DIN/ASA/ISO film senstivety and exposure values.
There was a reason that Tri-X was considered "fast" in the good old days.We had ilford film caled HP... I was tolf that the H refered to High and the P Panchromatic not sure if it was true.
We were also hampered by the mechanical limitions of the cameras of the day. Both of my 60's and 70's vintage Pentax SLRs were limited to 1/1000s shutter speed.I nver considered it hampering, in th UK the chances of using 1/1000 were limited by the weather ;-) The only time I used 1/1000th was to test it's speed/accuracy and when attempting pictures of the sun.
One of the reasons I loved my Yashica Electro 35 was that astonishing 1/2000 capability. Sometimes we don't appreciate just how much has changed when it comes to the capability of today's equipment when it comes to sensor sensitivity nd high shutter speed.Perhaps true with teh sensors but most othe rthings haven;t improved as fast as in other areas. Wow yeah fastest shutters speed in the 70s was about 1/1000th now it's 1/8000. Aperatures haven't changed that much compared to the 70s although the image quality has improved. but processor speeds were 1-2MHz or less now we have 3+GHz with multi-cores TVs 20" was large now the average seems to be 50". Perhaps even the relibility and performance/price of cars has increased more than cameras have.
And as for phones there;s just no comparision.
Now we have to transpose that theory to the digital universe with sensors, and without arguing as to how it is implemented and all that, it is still easiest to think of ISO for sensors as an analogy for film emulsion sensitivity.Yes that did seem to be a sensible way to go, thinking that people were using film and if they went to sensors how would they work out the correct exposure ? They must have thought well with this new way of getting pictures why not use terminoloy that people understand and are used to. We know we are now in a digital era so ideally we should have gone from 1/1000th to 1ms With all that in mind we can apply all the advantages of digital as nospam reminds us digital is best we can have our speed selection go from 1s to 500ms 250ms.... to 1ms the the new 1/1000 will be 1ms.
But I recon someone thought but photographers have alwas had the larger the number the less exposure tinme, now this is backwards and 1 isn;t 1 second but 1/1000th of a second, so I recon they thought nah stick with the old system that everyone knows in fractions of seconds. Now as for indicating the sensitivity of the sensor how should we do that. Lets see said one person lets redefine it, 100 ASA is close enough to the sensitivity of an female crayfishes eyes at a depth of 10 metres we should use that to describe brightness/sensitivity.
but luckily they thought why not just change ASA to ISO and use the same numerical values in the samne way to describe the same sensitivity as we had with film. Luckiy they chose this way. :-) DIN most likely got dropped as germany were the only other country producign film in any quantity that wasn't already using ASA.
to solve many of the exposure issues caused by the limitations of film.I'm not sure that's why it came about as in Oh will go to sensors as film is crap. Sensors were crap to begin with but those in teh electronics field new they could do better with time and new materials and will most likely exceed film in many ways.
01/06/2016-
